Long-term results of double-door laminoplasty for cervical stenotic myelopathy

Study Design, A retrospective study of the long-term results from double-do or laminoplasty (Kurokawa's method) for patients with myelopathy caused by ossification of the posterior longitudinal ligament and cervical spondylosi s was performed. Objective. To know whether the short-term results from double-door laminopl asty were maintained over a 10-year period and, if not, the cause of late d eterioration. Summary of Background Data. There are few long-term follow-up studies on th e outcome of laminoplasty for cervical stenotic myelopathy. Methods. In this study, 35 patients with cervical myelopathy caused by ossi fication of the posterior longitudinal ligament in the cervical spine and 2 5 patients with cervical spondylotic myelopathy, including 5 patients with athetoid cerebral palsy, underwent double-door laminoplasty from 1980 throu gh 1988 and were followed over the next 10 years. The average follow-up per iod was 153 months (range, 120-200 months) in patients with ossification of the posterior longitudinal ligament and 156 months (range, 121-218 months) in patients with cervical spondylotic myelopathy. Neurologic deficits befo re and after surgery were assessed using a scoring system proposed by the J apanese Orthopedic Association (JOA score). Patients who showed late deteri oration received further examination including computed tomography scan and magnetic resonance imaging of the cervical spine; Results. In 32 of the patients with ossification of the posterior longitudi nal ligament and 23 of the patients with cervical spondylotic myelopathy, m yelopathy improved after surgery. The improvement of Japanese Orthopedic As sociation scores was maintained up to the final follow-up assessment in 26 of the patients with ossification of the posterior longitudinal ligament an d 21 of the patients with cervical spondylotic myelopathy. Late neurologic deterioration occurred in 10 of the patients with ossification of the poste rior longitudinal ligament an average of 8 years after surgery, and in 4 of the patients with cervical spondylotic myelopathy, including the 3 patient s with athetoid cerebral palsy, an average of 11 years after surgery. The m ain causes of deterioration in patients with ossification of the posterior longitudinal ligament were a minor trauma in patients with residual cervica l cord compression caused by ossification of the posterior longitudinal lig ament and thoracic myelopathy resulting from ossification of the yellow lig ament in the thoracic spine. Conclusions. The short-term results of laminoplasty for cervical stenotic m yelopathy were maintained over 10 years in 78% of the patients with ossific ation of the posterior longitudinal ligament, and in most of the patients w ith cervical spondylotic myelopthy, except those with athetoid cerebral pal sy. Double-door laminoplasty is a reliable procedure for individuals with c ervical stenotic myelopathy.